1. Field of the Invention
The present invention relates to a noise reduction and signal compensating circuit. More particularly, the present invention relates to a circuit which compensates a received picture image of a high density television HDIV or general television and permits reception of a clear image without noise, and reduces deterioration in quality of a reproduced picture image occurring due to a variable reproduction speed in a videocassette recorder VCR (or video disk player VDP).
2. Description of the Prior Art
In a conventional television receiver, a method for improving the sharpness of a received picture image signal involves the use of a high pass filter (HPF) having a fixed frequency characteristic.
With such a conventional method, however, since the HPF is fixed in a high frequency filtering characteristic regardless of the condition of the received picture, the high frequency component of the noise signal is overemphasized in the picture image which has a relatively lower average brightness or the picture image has a relatively higher noise component.
As a result, picture quality is deteriorated remarkably and, hence, the background noise in the relatively dark picture image is increased considerably.
In accordance with the conventional method for television signal transmission, a band compressed transferring technique is used which employs a satellite broadcasting network of the HDTV. In such cases, a characteristic variation of transferring path is likely to occur due to a variation in weather conditions. Moreover, in the case of HDTV broadcasting using a land-controlled transferring technique, other problems are encountered, for example, a ghost image phenomenon related to multi-transferring paths in the HDTV broadcasting, interference between adjacent broadcasting channels, or deterioration of the picture quality in the long picture image recording or reproduction of a VCR (VDP).